A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
Xuchang, a prefecture-level city under the jurisdiction of Henan Province, also known as Liancheng, is located in the central part of Henan Province, one of the core cities of the Central Plains Urban agglomeration and the Central Plains Economic Zone; the terrain is high in the northwest and low in the southeast, slowly tilting from the northwest to the southeast; it belongs to the north warm temperate monsoon climate zone, rich in heat resources; it has jurisdiction over 2 districts, 2 county-level cities and 2 counties, with a total area of 4996 square kilometers; the permanent population is 4.4374 million in 2018. Xuchang is located in the Central Plains with a long history and is an important birthplace of Chinese culture. Xuchang ancient culture tourism resources include prehistoric culture series, Han culture series, three Kingdoms culture series, temple architecture culture series, Jun porcelain culture series and so on. Xuchang has convenient transportation, 80 kilometers away from the provincial capital Zhengzhou, 50 kilometers away from Xinzheng International Airport, 311 National Highway and local railway crossing east-west; Beijing-Guangzhou Railway, Beijing